The impact of urban groundwater upon surface water - eTheses ...

STUDY SETTING
boreholes perhaps suggesting reduction in association with organic pollution. Sulphate levels
may be raised by atmospheric fallout estimated at 275,000 kgy -1 (Ford, 1990), but the primary
loading is directly related to industry. Metal working industries return the highest average
values of 192 mgl -1 compared with 25 mgl -1 for the service industries.
High natural background levels of barium were observed in association with low sulphate
concentrations. Boron shows a clear correlation with land use and is indicative of
contamination by boric acid which is much used in the metals industry. Median values for
metal industry boreholes were 450 μgl -1 with service industry boreholes at < 20 μgl -1 .
Substantial concentrations of boron (30-150 μgl -1 ) were detected in the confined aquifer
related to release during gypsum dissolution. High levels of strontium (0.5-10 mgl -1 ) are
associated with natural occurrence within the confined aquifer. High levels of iron and
manganese are found to occur naturally as coatings within the sandstone and within the drift
deposits, providing a plentiful source for dissolution within the groundwater.
3.6.2 Organic Contamination
A survey of organic water quality (Rivett et al., 1990) indicated the chlorinated solvents
Trichloroethene (TCE), Trichloroethane (TCA), and Tetrachloroethene (PCE) to be the main
organic contaminants of the Birmingham Aquifer. The high levels of contaminants that were
detected were generally related to solvent user sites. The most widely occurring contaminant
was TCE which shows the greatest consumption of the chlorinated solvents by industry
within Birmingham. The solvent has been widely used since 1928 as a metal degreaser. TCA
was introduced as a replacement for TCE in 1965 but its use has declined because of its
detrimental effect on the ozone layer. PCE is used almost exclusively in Birmingham by the
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